Engine silencing hood



July 12, 1938. F. P. GRUTZNER ENGINE SILENCING HOOD Filed Jan. 29, 1937 2 Sheets-Sheet l July 12, 1938. F. P. GRUTZNER ENGINE .sxpsncnie noon Filed Jan. 29, 1937 2 Sheets-Sheet 2 Patented .July 12, 1938 PATENT OFFlCE ENGINE SILENCING HOOD Fritz Paul Grutzuer, Bcloit, Wis, assignor to Fairbanks, Morse & 00., Chicago, 111., a corporation oi. Illinois Application January 29, 1937, Serial No. 122,928

,5 Claims.

This invention relates to means for suppressing noise attending the operation of internal combustion engines, and more particularly to an improved silencing hood for internal combustion 6 engines, especially useful for Diesel-generator installations in residences, stores, theatres, and the like.

An object of the invention is to provide an improved silencing hood of thecharacter described 10 which is adapted to fit closely about the driving member of a Diesel-generator unit to completely house the same, and which is so constructed and mounted as to be readily removed and replaced for purposes of engine inspection or repair.

it Other objects and advantages will appear from the following detailed description and drawings accompanying the same, setting forth preferred embodiments of the invention as applied to a Diesci-generating unit.

2b In the drawings, Fig. l. is a side elevational View of such unit and silencing hood, with portions broken away to illustrate the preferred construction; Fig. 2 is an end elevation of the assembly illustrated in Fig. l with a portion of the silencing 25 hood broken away; Fig. 3 is a sectional view taken at line 3--3 of Fig. l, and Fig. i is an end elevation of an engine assembly and silencing hood therefor of alternate design.

Referring now by characters of reference to 30 the drawings, a Diesel-electric generating unit to which the silencing hood of the present invention is especially applicable includes an electric generator 5 operatively connected by a suitable coupling to the crank shaft of the engine, designated 35 8. The engine and generator are mounted on a unitary sub-base '5 having anchoring flanges 8 at the lower side edges thereoi; That portion of the sub-base which underlies and supports the engine is substantially of box-like construction,

40 having a bottom wall 9, side walls E0, and endwalls ii. A top plate i2, surmcunting side and end walls l and il,'has suitable openings therein to accommodate the engine flywheel, oil-pan and other portions of the engine which extend below 45 the crank shaft. Side margins of the top plate l2 project outwardly beyond the side walls in of the sub-base, providing horizontal flanges l3 for receiving and supporting the silencing hood. For purposes of damping vibration and minimizing 60 the drum efiect of the box-like sub-base, the same may be partly filled with sand or gravel.

The sub-base is preferably anchored to a concrete foundation or other solid footing, which may constitute the flooring of the room in which 55 the unit is installed, by means of suitably spaced soundand vibration-damping mountings l4. Such mountings desirably comprise a bracket l5 fastened to the sub-base, a companion bracket l6 embedded or otherwise fixed to the foundation, and rubber blocks I! which interconnect vertical 5 arms of brackets l5 and I6.

The silencing hood is designed and constructed to fit over and enclose completely that part of the engine structure which rises above the subbase. The hood embodies a rounded top portion 10 it! which merges into vertical side walls l9 that terminate downwardly at the supporting flanges l3, and end walls 20 that are substantially coplanar with the sub-base end walls l l. The hood is divided longitudinally into two complementary sections at a vertical, medial plane, the sections being detachably secured together by threaded elements 2! which engage flanges 22 disposed at the mating margins of the paired sections.

Each hood section preferably includes an outer casing member 23 of sheet metal, and a shell 24 spaced inwardly of the casing 23, the casing and shell defining an air chamber 25 therebetween. At the inner surface of shell 24 is a layer 26 of sound-absorbing material such as felt or asbestos 25 fibre, confined between shell 26 and a foraminous or reticulate inner lining member 21.

Detachable securement of the hood to the sub base structure is preferably accomplished by means of bolts 28 pivoted on arms 28 which ex- 30 tend laterally from flanges E3, the bolts being adapted to be swung into bifurcated, laterally projecting lugs 32 on the hood, wing-nuts 3i on bolts 28 serving to clamp the hood to the subbase. The broken line showing in Fig. 2 illus- 35 trates one of the hood sections as detached and displaced from its mating section.

Combustion air is drawn into the engine chamher through a filter silencer 32, of conventional type, mounted on one end of an intake pipe 33 which extends through an end wall of the hood.

That potrion of the intake pipe which isdisposed internally of the hood extends substantially parallel to the end wall and is provided with a multiplicityof perforations. An open-ended soundabsorbing casing 34 carried by the hood surrounds the perforated portion of the air intake pipe. The assembly thus described provides an eiiective muliier which checks sound transmission through the air intake opening in the hood. 0

Exhaust gases are discharged through a pipe 35 which projects through an opening .at the juncture of the upper edges of the casing sections, such opening being formed by complementary, semi-circular recesses in the casing =which the water pipe extends.

a flanged union 38, serving to conduct gases to the desired point of discharge. By the provision of flexible exhaust tubing, the transmission of engine vibration and sound through this connection is avoided.

Cooling water is conducted through flexible-tubing 39, Fig. 1, and a water pipe 40 which extends through openings in the engine sub-base. Metal to metal contactbetweenpipe 60 and the engine supporting structure is prevented by rubber sleeves 4| which line the openings in the sub-base through A conduit 42 connects the engine water jacket with the exhaust pipe water jacket 36, the cooling water being dis charged from the assembly through pipe 43.

Connections for fuel and lubricating oil are made through the sub-base, rubber silencing sleeves being provided at the conduit-openings for the fuel and oil pipes 44 and respectively. The engine starting and speed controls 46 in the present illustration shown as being inside'the hood, may be extended through suitable openings in the 'hood for external manipulation, in which event the opening in the hood for the control member should be provided with a rubber silencing sleeve.

An alternative construction of the silencing hood illustrated in Fig. 4 shows the hood extending to the floor or foundation, and being spaced.

on all sides from the engine. The hood is split centrally, and is similar in general constructionto the hood illustrated in Figs. 1 and 2. .However when this hood assembly is employed, flexible conduit for water, oil exhaust gases and fuel should extend between the engine and hood to permit the engine to oscillate on its resilient mounting relatively to the fixed hood, and to prevent transmission of sound and vibration to the hood.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A silencing hood for stationary internal combustion engines comprising a perforated inner casing member, an imperforate outer casing member paralleling said inner member, an'intermedi- 'ate shell spaced between said inner casing memher and shell, and sound-absorbing material-filling the space between the inner casing member and shell, said hood being divided at a vertical, longitudinal medial plane into paired, complemental sections, and means detachably securing said sections together.

2. In combination with an internal combustion engine, a base structure supporting the engine, a silencing hood enclosing the engine and carried by said ,base structure, said hood comprising top, side and end walls and being divided into complemental sections at a vertical, longitudinal, medial plane, means detachably securing said hood sections together, and means detachably sements, a plurality of ports or openings in said I upper enclosure and adapted to receive air and exhaust piping for the engine, and means for detachably securing the upper enclosure to said base structure.

4. In an engine-enclosing and sound-proofing structure, a hood formed of connected sections and adapted to be disposed about the upper portion of the engine, said hood being provided with openings to accommodate the engine airand exhaustpiping, and a hollow element in one of said openings providing a water jacket and adapted for connection to the engine cooling system, said element adapted to enclose 'an engine exhaust conduit and tending thermally to insulate said conduit from the hood structure.

5. In an engine-enclosing and sound-proofing structure, a hollow structure formed of detachably connected sections and a layer of fibrous insulating material carried by the walls of the hood structure, said structure being provided, between a pair of its connected sections, with an opening to pass the exhaust line from the engine, and an annular water jacket member adapted for connection to the engine cooling system, and disposed in said opening about the exhaust pipe.

FRITZ PAUL GRUTZNER. 

